Systems, methods and media for database synchronization on a network are disclosed. More particularly, hardware and/or software for database synchronization on a network protected with firewalls are disclosed. Embodiments include an e-mail listener for receiving e-mails from a plurality of computer systems and modifying a central database based on the received e-mails. In one embodiment, the computers systems and central database are protected by a firewall. Other embodiments provide for a transaction log that includes information about received e-mails. In these embodiments, the transaction log may optionally be used to synchronize other databases, including local databases located at the computer systems.